# \[API] Nghiên cứu về class WP\_REST\_Posts\_Controller (ok)

***1.public function get\_items***

Mặc định api <http://localhost/wordpress/wp-json/wp/v2/posts> chỉ lấy "type": "post"

![](/files/-MPCvQg383KfH5aDNea6)

Do đó nếu muốn lấy "type": "book" chẳng hạn :)

C:\xampp\htdocs\wordpress\wp-includes\rest-api\endpoints\class-wp-rest-posts-controller.php public function get\_items thay đổi thành :))

```
$args['post_type'] = array('post','book');
```

Đăng ký book ;)

C:\xampp\htdocs\wordpress\wp-content\themes\gutener\functions.php

![](/files/-MPCw6pprK42w50O0Vw7)

```
// ===========
add_action('init', 'my_book_cpt');
function my_book_cpt() {
  $labels = array(
    'name'               => _x('Books', 'post type general name', 'your-plugin-textdomain'),
    'singular_name'      => _x('Book', 'post type singular name', 'your-plugin-textdomain'),
    'menu_name'          => _x('Books', 'admin menu', 'your-plugin-textdomain'),
    'name_admin_bar'     => _x('Book', 'add new on admin bar', 'your-plugin-textdomain'),
    'add_new'            => _x('Add New', 'book', 'your-plugin-textdomain'),
    'add_new_item'       => __('Add New Book', 'your-plugin-textdomain'),
    'new_item'           => __('New Book', 'your-plugin-textdomain'),
    'edit_item'          => __('Edit Book', 'your-plugin-textdomain'),
    'view_item'          => __('View Book', 'your-plugin-textdomain'),
    'all_items'          => __('All Books', 'your-plugin-textdomain'),
    'search_items'       => __('Search Books', 'your-plugin-textdomain'),
    'parent_item_colon'  => __('Parent Books:', 'your-plugin-textdomain'),
    'not_found'          => __('No books found.', 'your-plugin-textdomain'),
    'not_found_in_trash' => __('No books found in Trash.', 'your-plugin-textdomain'),
  );
  $args = array(
    'labels'             => $labels,
    'description'        => __('Description.', 'your-plugin-textdomain'),
    'public'             => true,
    'publicly_queryable' => true,
    'show_ui'            => true,
    'show_in_menu'       => true,
    'query_var'          => true,
    'rewrite'            => array('slug' => 'book'),
    'capability_type'    => 'post',
    'has_archive'        => true,
    'hierarchical'       => false,
    'menu_position'      => null,
    'show_in_rest'       => true,
    'rest_base'          => 'books',
    'supports'           => array('title', 'editor', 'author', 'thumbnail', 'excerpt', 'comments'),
  );
  register_post_type('book', $args);
  flush_rewrite_rules(true);
}
// ===========
add_action('init', 'my_book_taxonomy', 30);
function my_book_taxonomy() {
  $labels = array(
    'name'              => _x('Genres', 'taxonomy general name'),
    'singular_name'     => _x('Genre', 'taxonomy singular name'),
    'search_items'      => __('Search Genres'),
    'all_items'         => __('All Genres'),
    'parent_item'       => __('Parent Genre'),
    'parent_item_colon' => __('Parent Genre:'),
    'edit_item'         => __('Edit Genre'),
    'update_item'       => __('Update Genre'),
    'add_new_item'      => __('Add New Genre'),
    'new_item_name'     => __('New Genre Name'),
    'menu_name'         => __('Genre'),
  );
  $args = array(
    'hierarchical'      => true,
    'labels'            => $labels,
    'show_ui'           => true,
    'show_admin_column' => true,
    'query_var'         => true,
    'rewrite'           => array('slug' => 'genre'),
    'show_in_rest'      => true,
    'rest_base'         => 'genre',
  );
  register_taxonomy('genre', array('book'), $args);
  flush_rewrite_rules(true);
}
```

Và kết quả như mong đợi :)

![](/files/-MPCwIApyjEklx6_iFxV)

**2. get\_collection\_params**

C:\xampp\htdocs\wordpress\wp-includes\rest-api\endpoints\class-wp-rest-controller.php

```
public function get_collection_params() {
	return array(
		'context'  => $this->get_context_param(),
		'page'     => array(
			'description'       => __( 'Current page of the collection.' ),
			'type'              => 'integer',
			'default'           => 1,
			'sanitize_callback' => 'absint',
			'validate_callback' => 'rest_validate_request_arg',
			'minimum'           => 1,
		),
		'per_page' => array(
			'description'       => __( 'Maximum number of items to be returned in result set.' ),
			'type'              => 'integer',
			'default'           => 10,
			'minimum'           => 1,
			'maximum'           => 100,
			'sanitize_callback' => 'absint',
			'validate_callback' => 'rest_validate_request_arg',
		),
		'search'   => array(
			'description'       => __( 'Limit results to those matching a string.' ),
			'type'              => 'string',
			'sanitize_callback' => 'sanitize_text_field',
			'validate_callback' => 'rest_validate_request_arg',
		),
	);
}
```

```
public function get_context_param( $args = array() ) {
		$param_details = array(
			'description'       => __( 'Scope under which the request is made; determines fields present in response.' ),
			'type'              => 'string',
			'sanitize_callback' => 'sanitize_key',
			'validate_callback' => 'rest_validate_request_arg',
		);

		$schema = $this->get_item_schema();

		if ( empty( $schema['properties'] ) ) {
			return array_merge( $param_details, $args );
		}

		$contexts = array();

		foreach ( $schema['properties'] as $attributes ) {
			if ( ! empty( $attributes['context'] ) ) {
				$contexts = array_merge( $contexts, $attributes['context'] );
			}
		}

		if ( ! empty( $contexts ) ) {
			$param_details['enum'] = array_unique( $contexts );
			rsort( $param_details['enum'] );
		}

		return array_merge( $param_details, $args );
	}
```

![](/files/-MPIsgwnxY7B1eD37Uc4)

![](/files/-MPIsjmh5l_iX7Wc08-N)

C:\xampp\htdocs\wordpress\wp-includes\rest-api\endpoints\class-wp-rest-posts-controller.php

```
public function get_items( $request ) {
		// Ensure a search string is set in case the orderby is set to 'relevance'.
		if ( ! empty( $request['orderby'] ) && 'relevance' === $request['orderby'] && empty( $request['search'] ) ) {
			return new WP_Error(
				'rest_no_search_term_defined',
				__( 'You need to define a search term to order by relevance.' ),
				array( 'status' => 400 )
			);
		}
		// Ensure an include parameter is set in case the orderby is set to 'include'.
		if ( ! empty( $request['orderby'] ) && 'include' === $request['orderby'] && empty( $request['include'] ) ) {
			return new WP_Error(
				'rest_orderby_include_missing_include',
				__( 'You need to define an include parameter to order by include.' ),
				array( 'status' => 400 )
			);
		}
		// Retrieve the list of registered collection query parameters.
		$registered = $this->get_collection_params();
		$args       = array();
		/*
		 * This array defines mappings between public API query parameters whose
		 * values are accepted as-passed, and their internal WP_Query parameter
		 * name equivalents (some are the same). Only values which are also
		 * present in $registered will be set.
		 */
		$parameter_mappings = array(
			'author'         => 'author__in',
			'author_exclude' => 'author__not_in',
			'exclude'        => 'post__not_in',
			'include'        => 'post__in',
			'menu_order'     => 'menu_order',
			'offset'         => 'offset',
			'order'          => 'order',
			'orderby'        => 'orderby',
			'page'           => 'paged',
			'parent'         => 'post_parent__in',
			'parent_exclude' => 'post_parent__not_in',
			'search'         => 's',
			'slug'           => 'post_name__in',
			'status'         => 'post_status',
		);
		/*
		 * For each known parameter which is both registered and present in the request,
		 * set the parameter's value on the query $args.
		 */
		foreach ( $parameter_mappings as $api_param => $wp_param ) {
			if ( isset( $registered[ $api_param ], $request[ $api_param ] ) ) {
				$args[ $wp_param ] = $request[ $api_param ];
			}
		}
		echo '<pre>';
			print_r($args);
		echo '</pre>';
		die();
		// Check for & assign any parameters which require special handling or setting.
		$args['date_query'] = array();
		// Set before into date query. Date query must be specified as an array of an array.
		if ( isset( $registered['before'], $request['before'] ) ) {
			$args['date_query'][0]['before'] = $request['before'];
		}
		// Set after into date query. Date query must be specified as an array of an array.
		if ( isset( $registered['after'], $request['after'] ) ) {
			$args['date_query'][0]['after'] = $request['after'];
		}
		// Ensure our per_page parameter overrides any provided posts_per_page filter.
		if ( isset( $registered['per_page'] ) ) {
			$args['posts_per_page'] = $request['per_page'];
		}
		if ( isset( $registered['sticky'], $request['sticky'] ) ) {
			$sticky_posts = get_option( 'sticky_posts', array() );
			if ( ! is_array( $sticky_posts ) ) {
				$sticky_posts = array();
			}
			if ( $request['sticky'] ) {
				/*
				 * As post__in will be used to only get sticky posts,
				 * we have to support the case where post__in was already
				 * specified.
				 */
				$args['post__in'] = $args['post__in'] ? array_intersect( $sticky_posts, $args['post__in'] ) : $sticky_posts;
				/*
				 * If we intersected, but there are no post IDs in common,
				 * WP_Query won't return "no posts" for post__in = array()
				 * so we have to fake it a bit.
				 */
				if ( ! $args['post__in'] ) {
					$args['post__in'] = array( 0 );
				}
			} elseif ( $sticky_posts ) {
				/*
				 * As post___not_in will be used to only get posts that
				 * are not sticky, we have to support the case where post__not_in
				 * was already specified.
				 */
				$args['post__not_in'] = array_merge( $args['post__not_in'], $sticky_posts );
			}
		}
		// Force the post_type argument, since it's not a user input variable.
		$args['post_type'] = array('post','book');
		/**
		 * Filters the query arguments for a request.
		 *
		 * Enables adding extra arguments or setting defaults for a post collection request.
		 *
		 * @since 4.7.0
		 *
		 * @link https://developer.wordpress.org/reference/classes/wp_query/
		 *
		 * @param array           $args    Key value array of query var to query value.
		 * @param WP_REST_Request $request The request used.
		 */
		$args       = apply_filters( "rest_{$this->post_type}_query", $args, $request );
		$query_args = $this->prepare_items_query( $args, $request );
		$taxonomies = wp_list_filter( get_object_taxonomies( $this->post_type, 'objects' ), array( 'show_in_rest' => true ) );
		if ( ! empty( $request['tax_relation'] ) ) {
			$query_args['tax_query'] = array( 'relation' => $request['tax_relation'] );
		}
		foreach ( $taxonomies as $taxonomy ) {
			$base        = ! empty( $taxonomy->rest_base ) ? $taxonomy->rest_base : $taxonomy->name;
			$tax_exclude = $base . '_exclude';
			if ( ! empty( $request[ $base ] ) ) {
				$query_args['tax_query'][] = array(
					'taxonomy'         => $taxonomy->name,
					'field'            => 'term_id',
					'terms'            => $request[ $base ],
					'include_children' => false,
				);
			}
			if ( ! empty( $request[ $tax_exclude ] ) ) {
				$query_args['tax_query'][] = array(
					'taxonomy'         => $taxonomy->name,
					'field'            => 'term_id',
					'terms'            => $request[ $tax_exclude ],
					'include_children' => false,
					'operator'         => 'NOT IN',
				);
			}
		}
		$posts_query  = new WP_Query();
		$query_result = $posts_query->query( $query_args );
		// Allow access to all password protected posts if the context is edit.
		if ( 'edit' === $request['context'] ) {
			add_filter( 'post_password_required', '__return_false' );
		}
		$posts = array();
		foreach ( $query_result as $post ) {
			if ( ! $this->check_read_permission( $post ) ) {
				continue;
			}
			$data    = $this->prepare_item_for_response( $post, $request );
			$posts[] = $this->prepare_response_for_collection( $data );
		}
		// Reset filter.
		if ( 'edit' === $request['context'] ) {
			remove_filter( 'post_password_required', '__return_false' );
		}
		$page        = (int) $query_args['paged'];
		$total_posts = $posts_query->found_posts;
		if ( $total_posts < 1 ) {
			// Out-of-bounds, run the query again without LIMIT for total count.
			unset( $query_args['paged'] );
			$count_query = new WP_Query();
			$count_query->query( $query_args );
			$total_posts = $count_query->found_posts;
		}
		$max_pages = ceil( $total_posts / (int) $posts_query->query_vars['posts_per_page'] );
		// Có 40 bài viết và link như sau http://localhost/wordpress/wp-json/wp/v2/posts?context=view&page=1&per_page=10
		// <pre>4.0</pre>
		if ( $page > $max_pages && $total_posts > 0 ) {
			return new WP_Error(
				'rest_post_invalid_page_number',
				__( 'The page number requested is larger than the number of pages available.' ),
				array( 'status' => 400 )
			);
		}
		$response = rest_ensure_response( $posts );
		$response->header( 'X-WP-Total', (int) $total_posts );
		$response->header( 'X-WP-TotalPages', (int) $max_pages );
		$request_params = $request->get_query_params();
		// array (
		//   'context' => 'view',
		//   'page' => 2,
		//   'per_page' => 2,
		// )
		$base           = add_query_arg( urlencode_deep( $request_params ), rest_url( sprintf( '%s/%s', $this->namespace, $this->rest_base ) ) );
		if ( $page > 1 ) {
			$prev_page = $page - 1;
			if ( $prev_page > $max_pages ) {
				$prev_page = $max_pages;
			}
			$prev_link = add_query_arg( 'page', $prev_page, $base );
			$response->link_header( 'prev', $prev_link );
		}
		if ( $max_pages > $page ) {
			$next_page = $page + 1;
			$next_link = add_query_arg( 'page', $next_page, $base );
			$response->link_header( 'next', $next_link );
		}
		return $response;
	}
```


---

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```
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